In the grade 10 science curriculum, the unit on physics has students learning about optics (the study of the properties and behaviour of light). We look at what the characteristics of light are, as well as how light behaves. After we learn the characteristics of light, and just before we look at how light behaves, we spend a little bit of time talking about what the different sources of light are.
- Chemiluminescence – light from chemical reactions
- Bioluminescence – light from biological organisms
- Incandescence – light from hot objects
- Electric Discharge – light from electricity passing through a gas
Both incandescence and electric discharge are fairly familiar to students. Incandescence is how incandescent light bulbs produce light (the thin tungsten filament gets very hot and emits light) and electric discharge can be observed every time we see lightning. Of the remaining two, bioluminescence and chemiluminescence, chemiluminescence can be demonstrated using household bleach and a substance called luminol. With a little bit of preparation using water and sodium hydroxide, the two solutions react to produce a striking blue light that glows in the dark.